Power

STK1005 supports a variety of power options.

Image:stk1005_power.jpg

Main supplies

For normal operation the power headers (1) must all have jumpers (these are intended for power measurements).

In addition the Vbat pin (2) must be supplied with 1.8-3.3V. Normally this is achieved with a jumper on this header. Alternatively a backup battery can be connected to Vbat.

Shutdown control and battery operation

When a battery is connected to Vbat it makes sense to use the shutdown controller embedded within AP7200. The shutdown controller outputs are available on the (not mounted) pin header (4). pin 2 is connected directly to the SHDN pin on AP7200 (active high). pin 1 is the inverted signal of SHDN.

The WAKE button will bring AP7200 out of shutdown mode.

Controlling MMC/SD voltage

AP7200 also supports both 1.8 and 3.3V MMC/SD cards on the STK1005 MMC4 connector (top, secondary side). The voltage level can be controlled with a GPIO pin connected to pin 1 of the header (3). The voltage can also be manually controlled. With pin 1 left floating the VCC_mmc is 3.3V, With a jumper to pin 2 (gnd) the voltage is 1.8 V.